Speaking after her third-round victory over Ana Konjuh, the Croatian player, on Friday, Wozniacki, said: "Usually I don't wear coloured underwear whenever you have to wear white. If the colour of the bra is really bright and the top is see-through, you can see it."

The Danish player added: "I don't think anyone is showing off their underwear like that and getting it checked. That would be pretty creepy."

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In previous years, players such as Serena Williams have worn colourful underwear to brighten up their tennis whites. Wozniacki had little sympathy for players who breached the regulations. "I think everyone was told before Wimbledon you have to wear white," she said. "I don't think there should be any surprises, really."

Pat Cash, the former Wimbledon champion, has claimed that there was disquiet over the new rules in the locker room.

He criticised the "archaic thinking", and said that championship officials were behaving "ridiculously" over the issue.

He said that some women had been told to change their bras and those without replacements were playing braless. It is understood that one male tennis player was told to change his black underpants.

Barbora Zahlavova Strycova, the Czech player, criticised the guidelines: "I think it's very weird to check under my skirt [to see] if I'm wearing white underwear. If we [are] playing in white, we should wear white underwear. But it's kind of weird officials coming and checking."

Belinda Bencic, the Swiss player who won her second-round match on Friday, supported the restrictions. "White at Wimbledon is a nice tradition," she said.

Simona Halep, of Romania, said that the dress code was part of what made the tournament "special".

Wozniacki also rejected suggestions of a link between her relationship with Rory McIlroy, the golfer, and her form on court. The golfer broke off their engagement last month. She denied that she "seemed to do better when Rory is not about". "My private life has nothing to do with my tennis," she said.